In the livestock industry, a primary factor for determining the value of a slaughtered animal carcass is the lean content of the carcass. Historically, various techniques have been devised to determine a grade or quality rating of an animal carcass. Various prior art techniques and devices are known which provide some indication of such information.
After a meat animal such as a beef or hog is slaughtered, it may be graded for lean content and/or quality by a grader who evaluates each carcass. At the present time, grading is typically done by visual inspection. Since the grade assigned to a carcass determines the value per pound for the carcass, grading has a significant economic impact. It is also well known that small variations in grading can have a large impact on the price received for a carcass.
A method and apparatus for ultrasonically grading a carcass is disclosed in U.S. Pat. No. 4,785,817 to Stouffer. The Stouffer method and apparatus include multiple transducers for ultrasonically creating a video image corresponding to a cross section of the animal carcass. The transducer head of the Stouffer device includes a linear array of transducer elements in conventional manner which are held by the transducer support unit in a generally horizontal position. The image produced by the Stouffer device is typically of the ribeye (beef) or loin eye area (pork) of the carcass. It is suggested in Stouffer that the grade of the carcass may be evaluated automatically by means of a computer using a suitable pattern recognition device which transfers information to the computer derived from the video or electronic image of the loin eye area.
Other ultrasonic devices for grading live animals and animal carcasses are disclosed in European Patent No. 0337661 to Wilson and the Carlson patents, U.S. Pat. Nos. 4,359,055 and 4,359,056. The Wilson patent discloses a hand held ultrasonic transducer unit which includes mutiple ultrasonic transducers. Scanning is preferably carried out on live animals with the Wilson device. The Wilson and the Carlson devices enable determination of skin/fat layer thicknesses and the muscle layer adjacent to the fat. The primary intent of the Carlson devices is for determining the thickness of the back fat of a live animal, particularly a pig or swine. The transducer of the Carlson device produces pulses which are amplified and supplied to a threshold detector and counted by an electric counter. The gain of the amplifier is varied in accordance with the number of counts detected by the counter device until the first fat layer is detected.
None of the aforementioned prior art devices enable precise determination of the area of the longissimus muscle of the animal as well as fat thickness in rapid fashion, i.e. in a manner rapid enough to evaluate carcasses at a rate suitable for use in a typical slaughterhouse application. Thus, an accurate high-speed, high volume device which enables a determination of carcass value relating to the grade, quality and lean content of the carcass is needed.